1. Field of the Invention
The present invention relates to a circular saw blade, and more particularly to a saw blade for longitudinally sawing lumber.
2. Description of the Prior Art
A circular saw, when used for making longitudinal cuts in lumber, usually in the direction of the wood grain, must be guided to prevent the saw from making a distorted cut or from binding itself in the cut due to the cut being diverted. The saw can be diverted because it will tend to follow the grain in the wood which may not be exactly parallel to the longitudinal axis of the lumber piece. In the past, single edger saws could have machine mounted guide members for guiding the saw and keeping it true while a cut is being made.
However, with the increasing use of multi-saw canters and edgers, it is not possible to provide machine mounted guide members. Rather, it is necessary to develop a self-guiding saw blade.
U.S. Pat. No. 3,344,822, A. P. Wilder, inventor, illustrates a circular saw blade having peripheral teeth and linear planing elements secured to the surface of the saw blade and extending somewhat radially. The planing elements of the Wilder saw are of the same width or slightly wider than the kerf of the saw.
Canadian Pat. Nos. 873,127 and 964,557, both naming Keene S. Strobel as inventor and assigned to Weyerhaeuser Company, describe the well-known "Strobe" saw which comprises a circular saw having peripheral teeth and a plurality of slots extending inwardly from the periphery of the saw. The slots being faced on the cutting edge of the slot are faced with a cutting element having the width of the kerf of the saw teeth.
All of these prior art patents show the use of linear elongated elements provided in a generally radial direction on a circular saw blade with the combined width of these linear elements being substantially the width of the kerf of the saw. The linear elements are also provided with cutting edges for the purpose of planing the wood and removing the sawdust from the cut. The Strobe saws include the slots presumably to reduce heat built up in the saw and to clear away sawdust from the planing action of the linear members and is an improvement on Wilder.
It has now been discovered that the linear members on the saw blades also function as self-guiding members for the saws, thereby overcoming the problems described earlier with respect to cutting longitudinal lumber with circular saws. However, problems are encountered with the Wilder saw resulting from serious heat buildup in the plane of the blade due to the extended cutting edges. Thus, distortion results in the blade.
Strobel suggests placing slots ahead of Wilder's cutting elements to dissipate the heat but creates other problems as documented in U.S. Pat. No. 4,123,958, Wright et al, which alleges to be an improvement over the Strobel patents. The provision of slots in the plate of the blade actually weakens the blade. Wright et al breaks up the linear elements into shorter cutting elements interrupted by slots. However, the Wright et al saw would no longer have any inherent self-guiding properties.